The classes command groups a collection of numbers into intervals.
or:
or:
| classes([0,0.5,1,1.5,2,2.5,3,3.5,4],0,2) | 
| 
 | 
| classes([0,0.5,1,1.5,2,2.5,3,3.5,4],-1,2) | 
| 
 | 
| classes([0,0.5,1,1.5,2,2.5,3,3.5,4],1,[1,3,5]) | 
| 
 | 
| classes([0,0.5,1,1.5,2,2.5,3,3.5,4],[1..3,3..6]) | 
| 
 |